Interaction between isotropic turbulent fields of different scales

The interaction between two isotropic fields of different scales has been analyzed by using the Eddy Damped Quasi Normal Markovianized (EDQNM) closure. While the experimental investigation can be easily carried out only when the disturbance is of smaller scale than the large scale of the background field, the theoretical approach can be carried out without any difficulty with the disturbance centered around any desirable kB. The results show completely different behaviors depending on the scale of the disturbance. When the disturbance is located at high wave number, it is dissipated in a very short time and the background field is not affected by the disturbance. When the disturbance is centered in the equilibrium range the energy is transfered towards both k greater than kB and k less than kB. The effect in the region k less than kB lasts longer than in the k greater than kB region. The effect on the background field is largest when the disturbance is in the energy containing region.